Flexible Pipe Connector and Manufacturing Method Therefor

The present invention relates to a flexible pipe connector to which a fluid transport pipe is connected, and more specifically, to a flexible pipe connector and a manufacturing method therefor which prevent a corrugated pipe made of a metal from be cracked or ruptured and absorb vibration by covering the corrugated pipe with a braided net woven with steel wires.

In a case in which a pipe or a connector therefor is likely to be bent during use or due to the narrowness of an installation place when a fluid transport pipe is connected to a predetermined device or fluid transport pipes are connected to each other, a flexible pipe connector having a predetermined flexibility with no concern of rupturing or damage even when the pipe or the connector therefor is bent is used.

For example, a flexible pipe connector is used for piping for supplying a high-pressure fluid such as a refrigerant for an air conditioner, a combustion gas for a heating device, or a liquid for fire extinguishing.

The flexible pipe connector described above includes a corrugated pipe having a plurality of alternately formed roots and crests through which a fluid passes, and a braided mesh woven with stainless steel wires, which covers the corrugated pipe to prevent the corrugated pipe from being stretched or ruptured.

However, the related art has a problem that incomplete welding occurs between the braided mesh and a base metal of a welded portion, a welding structure is complicated, and the numbers of welding processes and components increase, leading to higher manufacturing costs and longer manufacturing time for the flexible pipe connector.

Further, the related art has problems that components collide with each other during vibration, causing damage to the components, and that, when a hardness of a corrugated pipe falls below or exceeds a predetermined range, the corrugated pipe is bent or ruptured due to failing to absorb the vibrations.

In particular, when a flexible pipe connector is installed in a device in which vibration occurs continuously, an end portion of a metal corrugated pipe and a braided mesh covering the end portion of the corrugated pipe are severely abraded due to vibration, causing a crack in the end portion of the corrugated pipe, resulting in a problem that a refrigerant passing through the corrugated pipe leaks to the outside.

Further, in the related art, a flexible pipe connector in which components are welded using a gas silver brazing scheme has not only inconvenience of having to perform welding work on components to be welded together for each welded portion, but also a problem that a surface oxidation phenomenon and welding stress occur in a weld bead portion and surroundings thereof during welding work, and grain boundary carbide precipitation and stress corrosion cracking gradually occur over time in the welded portion, making the connector vulnerable.

Meanwhile, in the corrugated pipe that transports a fluid, a phenomenon that vibration of a compressor that compresses a refrigerant gas is transmitted to a piping line of a closed circuit may occur. Specifically, stress corrosion occurs and hardness becomes 240 Hv or more due to welding stress (welding stress of a thin-walled straight pipe) and corrugation processing stress (martensite structure formation) generated in a manufacturing process for a corrugated pipe, resulting in insufficient bending flexibility of the corrugated pipe and insufficient vibration absorption in a short corrugated pipe so that vibration is transmitted to the piping line of the closed circuit and the purpose of use of the flexible pipe connector is lost.

In order to solve the above problem, a corrugated pipe with improved elasticity and vibration absorption can be obtained by adding an annealing heat treatment process to a manufacturing process.

However, welding stress and processing stress can be removed through a manufacturing process further including the annealing heat treatment process in the related art, but since the flexibility of the corrugated pipe increases, a bending phenomenon according to a vibration amplitude occurs in the corrugated pipe side adjacent to a compressor (or pump) in which vibration occurs, this phenomenon is accumulated as much as a frequency, and processing stress is generated locally and intensively in a bent portion and accumulated, resulting in a fatal problem of occurrence of crack and corrosion.

An object of the present invention is to solve various problems of the related art above described.

Another object of the present invention is to provide a flexible pipe connector and a manufacturing method therefor that allow a welding structure of a flexible pipe connector to be simplified, improve welding quality, and reduce production costs.

Still another object of the present invention is to provide a flexible pipe connector and a manufacturing method therefor that allow a corrugated pipe and an end ring to be closely coupled.

Still another object of the present invention is to provide a flexible pipe connector and a manufacturing method therefor capable of preventing a corrugated pipe from being cracked by reducing friction between the corrugated pipe and a braided net covering the corrugated pipe even when large and small vibrations continuously occur, to prevent the corrugated pipe and the braided net from being damaged even during long-term use, thereby improving the reliability of a product and extending the life of the product.

Still another object of the present invention is to provide a flexible pipe connector and a manufacturing method therefor capable of improving work efficiency by allowing a welding ring to be easily inserted into an end portion of a braided mesh.

Still another object of the present invention is to provide a flexible pipe connector and a manufacturing method therefor that allow brazing welding between components to be simultaneously performed by performing a single heating process in a heat treatment furnace, and allow a processing hardening heat treatment work to remove stress generated during welding or metal processing.

Still another object of the present invention is to provide an annealing heat treatment hardness for removing welding stress and processing hardening generated in a manufacturing method for a corrugated pipe and increasing spring elasticity of the corrugated pipe, since a corrugated pipe produced through a manufacturing process including an annealing heat treatment process of the related art is not suitable as a corrugated pipe for vibration absorption due to excessive flexibility with Vickers hardness being 160 HV to 170 HV and low spring elasticity.

The objects of the present disclosure are not limited to the objects mentioned above, and other objects that are not mentioned can be clearly understood by those skilled in the art from the description below.

According to an aspect of the present invention for achieving the above object, a flexible pipe connector includes a corrugated pipe, an end ring having one side portion inserted into and welded to an end portion of the corrugated pipe; a braided net woven with steel wires covering a portion of an outer circumferential surface of the end ring and an outer circumferential surface of the corrugated pipe; and a welding ring having an expanded pipe portion formed in one side portion, and inserted into the end ring so that an end portion of the braided net is disposed in a gap between the expanded pipe portion and the end ring, the end portion of the braided net being welded to the welding ring.

Meanwhile, according to an aspect of the present invention for achieving the above object, a method for manufacturing a flexible pipe connector includes applying a welding agent to an end portion of a corrugated pipe and inserting one side portion of an end ring into the end portion; covering a portion of an outer circumferential surface of the end ring and the corrugated pipe with a braided net, a welding agent being applied to an end portion of the braided net; inserting a welding ring into the end ring so that an expanded pipe portion of the welding ring covers the end portion of the braided mesh; and heating an assembly of the corrugated pipe, the end ring, the braided mesh, and the welding ring in a heat treatment furnace to melt the welding agent and then performing cooling.

According to an aspect of the present invention for achieving the above object, a flexible pipe connector includes a corrugated pipe, an end ring having one side portion inserted into and welded to an end portion of the corrugated pipe; a circular ring disposed on the end portion of the corrugated pipe; a braided net woven with steel wires covering a portion of an outer circumferential surface of the end ring, an outer circumferential surface of the corrugated pipe, and an outer circumferential surface of the circular ring; and a welding ring inserted into an outer side of the end ring, an end portion of the braided net being inserted into a gap between the welding ring and the end ring and welded.

The circular ring is disposed to protrude outward from the corrugated pipe beyond a crest of the corrugated pipe.

The circular ring may be partially inserted into a root between a crest at an extreme end formed in a one side end portion of the corrugated pipe and a crest adjacent to the crest at the extreme end, that is, a root formed at an extreme end among roots of the corrugated pipe.

The circular ring may be disposed between the crest at the extreme end of the corrugated pipe and the welding ring.

The circular ring may be a spring ring with one cut side.

The welding ring may have an expanded pipe portion formed in one side portion, and the end portion of the braided mesh may be inserted into the gap between the expanded pipe portion and the end ring and welded.

Further, the end ring may have a step portion formed in an one side portion having a smaller outer diameter than the other side portion, the step portion of the end ring and the end portion of the corrugated pipe may be welded, a shoulder portion may be formed between the other side portion of the end ring and the step portion, an vertical extension portion may be formed at an extreme end in the end portion of the corrugated pipe, and the shoulder portion of the end ring and the vertical extension portion of the corrugated pipe may be welded.

Further, the end portion of the braided mesh may be bonded to the outer circumferential surface of the end ring with an instant adhesive. Further, the end portion of the braided mesh may be temporarily bonded to the outer circumferential surface of the end ring with an instant adhesive.

Further, a front end portion of the expanded pipe portion of the welding ring may be formed as an inclined surface whose inner diameter gradually decreases inward.

Meanwhile, according to an aspect of the present invention for achieving the above object, a method for manufacturing a flexible pipe connector includes applying a welding agent to an end portion of a corrugated pipe and inserting one side portion of an end ring into the end portion; disposing a protective ring in the end portion of the corrugated pipe before or after the applying; covering a portion of an outer circumferential surface of the end ring, the corrugated pipe, and the protective ring with a braided net, a welding agent being applied to an end portion of the braided net; inserting a welding ring into the end ring so that an expanded pipe portion of the welding ring covers the end portion of the braided mesh; and heating an assembly of the corrugated pipe, the circular ring, the end ring, the braided mesh, and the welding ring in a heat treatment furnace to melt the welding agent and then performing cooling.

The method may include, after the step is completed, putting an assembly of the corrugated pipe, the end ring, the braided net, and the welding ring into a heat treatment furnace to heat the assembly so that the welding agent is melted, and then performing cooling.

Further, the step portion of the end ring may be inserted into the end portion of the corrugated pipe in a forced fit manner. The welding ring may be fitted and welded to an outer side portion of the end ring.

Further, in the welding ring, the end portion of the braided mesh may be inserted into an inner circumferential surface of the expanded pipe portion having a larger outer diameter than the other side portion. The expanded pipe portion of the welding ring, an outer diameter portion of the end ring, and the end portion of the braided mesh may be welded.

Further, the shoulder portion formed between the step portion of the end ring and the other side portion may be inserted into an extreme end of the corrugated pipe and welded.

Further, the welding ring may be processed so that a portion covering the end portion of the braided mesh is formed as an expanded pipe portion, and an inner circumferential surface of a front end portion of the expanded pipe portion is formed as an inclined surface.

Further, the method may include temporarily bonding the end portion of the braided mesh to the outer circumferential surface of the end ring with an instant adhesive for a metal before the welding ring is inserted into the end ring.

Further, the expanded pipe portion of the welding ring may be formed to have a relatively large inner diameter, the end portion of the braided mesh may be inserted into the expanded pipe portion, and then the expanded pipe portion may be compressed to minimize a welding gap between the expanded pipe portion and the end portion of the braided mesh.

Further, a plate-shaped ring, a circular ring, or an oval ring may be inserted between the corrugated pipe and the braided mesh to prevent cracks in a top portion of the crest of the corrugated pipe due to friction caused by vibration in an outer side portion (the top portion of the crest) of the corrugated pipe and the braided mesh.

Further, the flexible pipe connector according to the present disclosure may be heated at 1050° C. to 1150° C. in a heat treatment furnace for a predetermined time and then cooled so that component welding, corrugated pipe processing, and stress relief processes can be completed simultaneously.

Specific details of other embodiments are included in the detailed description and drawings.

The flexible pipe connector and a manufacturing method therefor according to the embodiment of the present invention have one or more of the following effects.

First, in the flexible pipe connector according to the embodiment of the present invention, since the corrugated pipe is covered by the braided net in a state in which the circular ring protruding outward beyond the crest of the corrugated pipe is disposed in the end portion of the corrugated pipe or the plate-shaped ring is disposed on the outer side beyond the crest of the corrugated pipe, the problem that a top portion of the crest of the corrugated pipe is worn and damaged (for example, holed or cracked) due to friction between the adjacent braided net and corrugated pipe is prevented even in an environment in which continuous vibration occurs for a long time.

Second, in the flexible pipe connector according to the embodiment of the present invention, since the step portion and the shoulder portion are formed on the outer circumferential surface of the end ring, and the end of the corrugated pipe and the shoulder portion are welded in a state in which the end of the corrugated pipe is in contact with the shoulder portion, a coupled state of the end ring and the corrugated pipe is securely maintained even when vibration or shock occurs for a long time.

Third, since an inner circumferential surface of a front end portion of the welding ring is formed as an inclined surface, and a right angle portion of the front end portion of the welding ring that comes into contact with the braided mesh is eliminated, not only can the end portion of the braided mesh be easily inserted along the inclined surface of the expanded welding ring, but also, the braided mesh is prevented from being damaged, ruptured, or cracked due to friction with a top portion of the outer crest of the corrugated pipe even when vibration, impact, or bending occurs for a long time since the inner circumferential surface of the front end portion of the welding ring that comes into contact with the braided mesh is formed as the inclined surface rather than a right-angled surface.

Fourth, since the end portion of the braided mesh is bonded to the end ring and then inserted into the welding ring, steel wires located in the end portion of the braided mesh can be neatly aligned and easily inserted into the welding ring.

Fifth, since the flexible pipe connector according to the present disclosure in which components are assembled is heated to a melting temperature of the welding agent within an annealing temperature range for stress relief of the corrugated pipe in a heat treatment furnace, a heat treatment process for relieving the processing stress and welding stress of the corrugated pipe and a welding process can be easily performed simultaneously.

The effects of the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by those skilled in the art from the description of the claims.

The advantages and features of the present invention and methods for achieving the advantages and features will become clear by referencing the embodiments that will be described in detail later together with the accompanying drawings. However, the present invention is not limited to the embodiments that will be disclosed below, but may be implemented in various different forms, the embodiments are provided only to make the disclosure of the present invention complete and to fully inform those skilled in the art to which the present invention belongs of the scope of the invention, and the present invention is defined only by the claims. The same reference signs refer to the same components throughout the specification.

When one portion is said to be “on” or “above” another portion throughout the specification, this includes not only a case in which the one portion is “directly over” the other portion, but also a case in which there is another portion in between. On the other hand, when a portion is said to be “directly over” another portion, this means that there is no other portion in between.